Intraluminal Graft

ABSTRACT

An intraluminal graft includes a tubular graft body extending along a cylindrical axis, a plurality of wires spaced apart from each other and arranged to circumferentially reinforce said tubular graft body along a substantial portion of its length, and a body surface including an inner surface region and an outer surface region. The body surface defines a plurality of apertures extending from an exterior space, and a first portion of a first wire is in the interior space while a second portion of the first wire is in the exterior space.

FIELD OF INVENTION

The present invention relates to an intraluminal graft for use intreatment of aneurysms or occlusive diseases.

It is known to use stents and intraluminal grafts of various designs forthe treatment of aneurysms such as aortal aneurysms and for thetreatment of occlusive diseases such as the occlusion of blood vesselsor like ducts such as the bile duct and the ureter (which are allhereinafter called “vessels”). It is known to form such an intraluminalgraft of a sleeve in which is disposed a plurality of self expandingwire stents (see Balko A. et al., “Transfemoral Placement ofIntraluminal Polyurethane Prosthesis for Abdominal Aortic Aneurysms”,Journal of Surgical Research 40, 305-309 (1986); Mirich D. et al,“Percutaneously Placed Endovascular Grafts for Aortic Aneurysms:Feasibility Study” Radiology, Vol. 170, No. 3, part 2, 1033-1037(1989)). Such intraluminal grafts are inserted through the femoralartery into the aorta in a catheter. Upon the release of the graft fromthe catheter it expands to the size of the aorta above and below theaneurysms and bridges the aneurysms.

There are a number of problems associated with such known grafts. Theseinclude the problem of twisting or kinking of the graft when it has toextend along a non-linear path which, twisting or kinking can lead toocclusion of the lumen of the grafts lack of precise control of theexpansion of the graft in the lumen; avoidance of inadvertent separationof a supporting stent and the covering sleeve; and maintaining the graftagainst longitudinal movement along the lumen in which it is placed. Thepresent invention is directed to an alternative form of intraluminalgraft which provides an alternative to the known grafts.

DISCLOSURE OF THE INVENTION

In a first aspect the present invention consists in an intraluminalgraft comprising a tubular graft body which is circumferentiallyreinforced along its length by a plurality of separate, spaced-apart,maleable wires, each of which has a generally cloned sinusoidal orzig-tag shape, one of the wires being located adjacent to one end of thegraft body such that alternate crests or apices of the wire projectsbeyond at least part of that end.

In another aspect the invention relates to a method for positioning anintraluminal graft as defined above comprising introducing a catheterinto a vein, artery or other vessel in the body, causing an intraluminalgraft as defined above to be carried through the catheter on aninflatable balloon until the graft extends into the vessel from theproximal end of the catheter, inflating the balloon to cause thealternate crests or apices of the one wire to be urged into contact withthe wall of the vessel, deflating the balloon and withdrawing theballoon and the catheter from the vessel.

In preferred embodiments of the invention each end of the graft will beprovided with a wire which has alternate crests or apices extendingbeyond the adjacent end of the graft body. While the graft will normallyhave wires at each end of the graft with their crests extending beyondthe graft body it may be necessary or desirable for a surgeon to shortena graft and this may be achieved by cutting off part of the graft body.In this case the graft will have extending crests at only one end.

The projection of alternate crests or apices of the end wire or wiresbeyond at least part of the end or ends of the graft body is animportant feature of this invention. As the graft is expanded by aballoon the expansion of the wires, and of the balloon, will be limitedby the diameter of the tubular graft body except in the region of thealternate crests or apices of the end wire or wires. The balloon will beable to expand these crests slightly more than the remainder of the wireso that they bell outwardly away from the adjacent end of the graftbody. The crests are forced into contact with the wall of the vessel andthereby become at least partly embedded into the vessel wall. Thisbelling out of the crests of the wires at one or both ends of the graftbody into contact with the inside surface of the vessel wall and thenbeing at least partly embedded in the wall will assist in resisting anytendency for the graft to wove longitudinally within the vessel afterinsertion. The wire crests may extend across the lumen of a vesselopening into the vessel in which the graft is being placed withoutoccluding that lumen. This allows the intraluminal graft to be used insituations in which the aneurysm to be bridged commences closelyadjacent divergent blood vessels. In most cases there will be crests ofwire actually projecting totally beyond the end of the graft materials.It would, however, be possible to have flaps of graft materialprotruding up the outside of each crest even though intermediate thecrests the end of the graft stops well short of the crests. In thislatter arrangement the crests are still free to bell outwardly as hasbeen described above even though the crests do not extend absolutelybeyond the end of the graft.

It is preferred that the one wire has a greater amplitude than at leastthe next adjacent one or two wires. This allows the wires at the end ofthe graft to be positioned more closely together than would be the caseif they were all of the same amplitude. It is desirable to space thewires adjacent the and of the graft that will be placed “upstream” inthe patient as close together as is possible as the neck of the aneurysmwith which the graft is engaged can be quite short. Close spacing of thewires maximises the number of wires reinforcing that part of the graftin contact with the neck of the aneurysm. The spacing of the rest of thewires is desirably greater than those adjacent the one end of the graftas this avoids unnecessarily reducing the flexibility of the graft.

The wavelength of the wires in the graft is preferably substantially thesame when compressed however when expanded the end wires will have ashorter wavelength than the intermediate wires as the intermediate wireswill not bear against the arterial wall and may therefore be more fullyexpanded.

It is preferred that the edge of the one end of the graft is scooped outor scalloped between each projecting crest of the one wire. This reducesthe possibility that a piece of the graft between those crests couldproject into the arterial lumen and partially occlude it or direct bloodaround the outside of the graft.

The tubular graft body is preferably formed of a thin biocompatiblematerial such an Dacron or PTFE. The tube material is preferably crimpedalong its length to increase its flexibility, however, uncrimpedmaterial may be used in suitable circumstances. In preferred embodimentsof the invention the graft body may be formed from a material having alimited amount of diametric elasticity to ensure that it can be expandedinto contact with the vessel wall. The length and diameter of the graftbody will be determined by the individual circumstances of theapplication to which the intraluminal graft is to be put. Typically, thevessel will be assessed by X-ray or other similar examination and asuitably dimensioned graft selected for that application.

The wires are preferably formed of stainless steel or another metal or aplastic which is maleable and is biocompatible. Each wire is preferablywoven into the fabric of the graft body to integrate the body and thereinforcing wires. This prevents any possibility of the wirereinforcement separating from the graft body during introduction of thegraft or throughout its life. If the graft body is of a woven materialthe wires may be interwoven with the graft body during its production oralternatively they may be interwoven with the graft body after itsmanufacture. If the graft body is not woven but is knitted or of animpervious sheet material then the wires may be threaded throughsuitable holes formed in the graft body. The interweaving of the wireswith the graft body has been found to be particularly desirable an itprevents separation of the wires from the graft body which could haveserious adverse consequences. It has also been found that this techniqueis very good for causing the graft to expand effectively with the wires.

In alternative embodiments the wires may be held in place by sutures oradhesives or may be sandwiched between layers of a multi-layered tubulargraft body. In all of the foregoing arrangements the wires arepreferably disposed substantially within the graft body. It is, however,within the ambit of the invention that the wires may be connected to,and be disposed on, the outside surface of the graft body.

The intraluminal grafts according to this invention may be used to treataneurysms or occlusive disease. In addition to treating aortic aneurysmsthey are particularly suitable for treating aneurysms of the femoralartery, the popliteal artery, the thoracic segment of the aorta,visceral arteries such as the renal and mesenteric arteries, the iliacartery and the sub-clavian artery. The presence of the metal wires inthe intraluminal grafts according to this invention assists in placingthe graft as the wires are X-ray detectable. As the wires are arrayedalong the length of the graft the complete position of the graft in thebody can be continuously monitored.

The grafts according to this invention are typically substantially ofconstant diameter along their length is, they are substantiallycylindrical. It is possible, however, for the grafts to befrusto-conical in shape with a diameter that increases, or decreases,along the length of the graft.

The ends of the wires are joined together to form a tail which ispreferably on the outside of the graft body and is positioned to liealong its radially outer surface. The ends may be joined by welding, bybeing twisted together or in any other suitable manner. The ends of thewires may inadvertently perforate the vessel in which the graft isplaced, however, any such perforation will be occluded by the graft bodythus ensuring that such a perforation will not adversely affect thepatient. The ends of adjacent wires are preferably spaced apart radiallyabout the graft body so as not to affect its flexibility and to avoid aline of ends engaging the wall of the vessel. The ends of adjacent wirespreferably project in opposite directions along the vessel body. Whenthe intraluminal graft is inserted into a vessel those wire ends whichengage the inside surface of the vessel wall will assist in preventingthe graft from inadvertent movement along the vessel. Causing the end ofalternate wires to project in opposite longitudinal directions along thegraft body will assist in preventing longitudinal movement of the graftalong the vessel in either direction.

In some circumstances it is desirable to insert two or more overlappedintraluminal grafts according to the present invention. In this case thefirst or upstream graft preferably has at its downstream end a “skirt”without reinforcing wires. This skirt is typically 10 to 15 mm inlength. The second or downstream graft is inserted into the downstreamend of the first graft and is expanded to engage with it. There ispreferably an overlap of at least 10 mm however the degree of overlap isoften adjusted so that the downstream end of the second graft iscorrectly placed in the downstream neck of the aneurysm being treated.This can lead to a greater overlap than is the minimum required but is auseful technique to ensure that the overall length of the graft iscorrect.

It is sometimes the case that the aneurysm extends up to or slightlybeyond an arterial bifurcation. In such a case it is possible to place agraft according to the present invention which has a bifurcation at itsdownstream end, a so-called “trouser graft”, wholly within the primaryartery. A supplemental graft may then be introduced through each of thesubsidiary arteries and overlapped with the respective lumenae of thebifurcated part of the primary graft. In the case of an aneurysm in theaorta, for instance, that extended into each of the iliac arteries theprimary graft of the “trouser” type would be placed in the aorta throughone of the iliac arteries. Supplemental grafts which dock with thebifurcated end of the primary graft would then be inserted through eachof the iliac arteries.

In those cases where one graft according to this invention is to beinserted into the downstream and of another such graft it may bedesirable to provide means to stop the “skirt” on the downstream and ofthe other graft from being distorted by the insertion of the one graft.This may conveniently be done in one or other of two ways. The skirt maybe provided with a small number of linear reinforcement wires extendinglongitudinally of the graft. In this case, the wires are spaced aboutthe circumference of the skirt. Alternatively, the skirt may be providedwith at least one resilient annular reinforcement wire. The resilientreinforcement wire will spring into an expanded condition upon beingreleased from the catheter through which it is introduced into the body.This latter arrangement is particularly suitable in the case of “trousergrafts” wherein one leg of the graft will have a skirt which cannot beexpanded by a balloon catheter.

BRIEF DESCRIPTION OF DRAWINGS

Hereinafter given by way of example is a preferred embodiment of thepresent invention described with reference to the accompanying drawings,in which:—

FIG. 1 is a diagrammatic partially cut-away ventral view of a patientwith an aortic aneurysm which has been bridged by an intraluminal graftaccording to the present invention;

FIG. 2 is a side elevational view of the intraluminal graft of FIG. 1;

FIG. 3 is a longitudinal sectional view through the intraluminal graftof FIG. 2;

FIG. 4 is a detailed longitudinal sectional view through theintraluminal graft of FIG. 2 as it is being expanded into contact withthe aorta of a patient during placement;

FIG. 5 is a detailed longitudinal sectional wire through theintraluminal graft of FIG. 2 after it has been inserted into the aortaof a patient;

FIG. 6 is a detailed elevational view of one end of the intraluminalgraft of FIG. 2; and

FIG. 7 is a detailed perspective view of the one end of the intraluminalgraft of FIG. 6 showing how the alternate crests of the end wire of thegraft are pushed radially outwardly during insertion of the graft.

BEST MODE OF CARRYING OUT THE INVENTION

The intraluminal graft 10 is adapted for insertion transfemorally into apatient to achieve bridging and occlusion of the aneurysm present in theaorta. As is seen in FIG. 1 the aorta 11 is connected to the left andright femoral arteries 12 and 13. The aortic aneurysm is located betweenthe renal arteries 14 and 15 and the junctions of the femoral arteries12 and 13 with the aorta 11. The graft 10 is, as will be describedsubsequently in more detail, inserted inside a catheter introduced intoone of the femoral arteries 12 or 13 in a leg of the patient. Once thecatheter is located appropriately with its proximal end in the aorta 11the graft 10 is ejected from the catheter and expanded so that each endis in intimate contact around its full periphery with the aorta 11. Thegraft 10 then bridges the aneurysm and isolates any thrombosis orgelatinuous material associated with the aneurysm outside the graft 10to reduce the risk of embolisation.

The intraluminal graft 10 comprises a crimped tube 16 of woven Dacron.The tube is reinforced along its length by a number of separate andspaced apart stainless-steel wires 17 (each of which has a generallyclosed sinusoidal shape). The wires 17 are preferably as thin aspossible and are typically 0.3 to 0.4 mm in diameter. The wires 17 aremaleable and may be bent into any desired shape, is they are notresilient to any substantial extent so that they have to be physicallyexpanded into contact with the aorta rather than expanding by virtue oftheir own resilience. The wires 17 are each woven into the fabric of thetube 16 such that alternate crests of each wire 17 are outside the tube16 with the remainder of that wire 17 inside the tube (except in thecase of the endmost wires as will be hereinafter described). The ends ofeach wire 17 are located outside the tube 16 and are twisted together toform a tail 18. The tails 18 of alternate wires 17 are bent to extend inopposite longitudinal directions along the outside surface of the tube16.

The endmost ones of the wires 17 overhang the respective ends of thetube 17 so that alternate crests of those wires extend longitudinallybeyond the end of the tube 16. The endmost wire 17 preferably has anamplitude of about 6 mm and a wavelength such that between six and eightcrests are spaced around the circumference of a 22 mm diameter graft.The next two adjacent wires 18 preferably are spaced as close aspossible to the wire 17 and respectively have amplitudes of 4 mm and 5mm. These wires will typically have the same wavelength initially an thewire 17. Thereafter throughout the graft 10 the wires 18 are spaced at15 mm intervals, have an amplitude of 6 mm, and have substantially thesame initial wavelength as the wire 17.

In use the graft 10 is radially compressed about an inflation balloon 19(see FIG. 4) and the assembly is inserted into the end of a sheathcatheter 21. The sheath catheter 21 is inserted in a known mannerthrough the femoral artery into the aorta 11 until the proximal end ofthe catheter 21 is beyond the proximal and of the aneurysm. The balloon19 and the collapsed graft 10 disposed on it, are held stationary andthe catheter withdrawn until the graft 10 is fully exposed and spans theaneurysm. The balloon is then inflated to expand the graft 10. Thediameter of the tube 16 determines the maximum expansions of themajority of the graft 10 and this diameter has been selected in advanceby X-ray examination, or the like, to be substantially equal or onlyvery slightly larger than, the diameter of the undistended aorta 11. Theballoon is, however, able to expand the alternating crests of the endwires 17 so that they are pushed firmly into contact with the wall ofthe aorta. These radially outwardly displaced crests serve to moreeffectively restrain the graft 10 against longitudinal movement relativeto the aorta.

1-11. (canceled)
 12. A method of placing an intraluminal graft in anaortic artery, comprising: positioning, in said aortic artery, anintraluminal graft; wherein said intraluminal graft includes a wireapice connected to a first graft body; wherein said wire apice extendsfrom an aortic artery first region of said aortic artery, said aorticartery first region being between a femoral artery and a renal artery,to an aortic artery second region, said aortic artery second regionbeing on an opposite side of said renal artery from said femoral artery.13. The method of claim 12 wherein said first graft body does notocclude said renal artery.
 14. The method of claim 12 wherein said firstgraft body resides in said aortic artery below said renal artery. 15.The method of claim 14 wherein said first graft body resides betweensaid renal artery and said femoral artery.
 16. The method of claim 12wherein said intraluminal graft comprises a second graft body, andfurther comprising partially inserting said second graft body into saidfirst graft body inside of said aortic artery.
 17. The method of claim12 wherein said positioning places graft body material of saidintraluminal graft facing an aneurysm.
 18. The method of claim 12wherein said positioning places graft body material of said intraluminalgraft facing an occlusion.
 19. The method of claim 12 wherein said firstgraft body has a tubular shape.
 20. The method of claim 12 wherein saidpositioning comprises pressing said wire apice against an inner surfaceof said aortic artery using a balloon.
 21. The method of claim 12wherein said wire apice is part of a first wire, and said first wire hasa shape that is generally closed sinusoidal.
 22. The method of claim 12wherein said wire apice is part of a first wire, and said first wire hasa shape that is generally closed zig-zag.
 23. The method of claim 12wherein said wire apice is part of a first wire, and further comprisingat least a second wire not at an end of said intraluminal graft.
 24. Themethod of claim 23 wherein said first wire forms a closed loop and saidsecond wire forms a closed loop.
 25. The method of claim 24 wherein saidfirst wire and said second wire are not connected by wire to oneanother.
 26. The method of claim 12 wherein said wire apice is part of afirst wire, and further comprising at least a second wire not at an endof said first graft body and a third wire not at an end of said firstgraft body.
 27. The method of claim 26 wherein said first wire, saidsecond wire, and said third wire are not connected by wire to oneanother.
 28. The method of claim 12 wherein said wire apice is part of afirst wire, and wherein said wire apice is one of a plurality of wireapices of said first wire, and wherein at least two of said plurality ofwire apices extend beyond said first graft body.
 29. A method of placinga prosthesis in an aortic artery, said prosthesis having a first end anda second end, said prosthesis comprising a graft body and a wirestructure, said wire structure including a plurality of wire apices thatextend beyond said first end, said method comprising: positioning saidprosthesis such that said plurality of wire apices extend across a renalartery, and such that said graft body does not occlude said renalartery.
 30. The method of claim 29 further comprising expanding aballoon to press said wire apices against an inner surface of saidaortic artery.
 31. A method of placing a prosthesis in an aortic artery,said prosthesis having a first end and a second end, said prosthesiscomprising graft body and a wire structure, said wire structureincluding a plurality of wire apices that extend beyond said first end,said method comprising: positioning said prosthesis such that saidplurality of wire apices extend across a renal artery, and such thatsaid graft body does reside in said renal artery.
 32. The method ofclaim 31 further comprising expanding a balloon to press said pluralityof wire apices against an inner surface of said aortic artery.
 33. Amethod of placing a prosthesis in an aortic artery, said prosthesishaving a first end and a second end, said prosthesis comprising graftbody and a wire structure, said wire structure including a plurality ofwire apices that extend beyond said first end, said method comprising:positioning said prosthesis such that said plurality of wire apicesextend across a renal artery, and such that said graft body does notface said renal artery.
 34. The method of claim 33 further comprisingexpanding a balloon to press said plurality of wire apices against aninner surface of said aortic artery.
 35. A method of placing aprosthesis in an aortic artery, said prosthesis having a first end and asecond end, said prosthesis comprising a graft body and a wirestructure, said wire structure including a plurality of wire apices thatextend beyond said first end, said method comprising: positioning saidprosthesis such that said plurality of wire apices extend across a renalartery, and such that said graft body is not in an intersection of saidaortic artery with said renal artery.
 36. The method of claim 35 furthercomprising expanding a balloon to press said plurality of wire apicesagainst an inner surface of said aortic artery.